A method for determining a vehicle reference velocity is described in German Patent No. DE 102 59 272 A1, in which various calculation paths are followed on the basis of acceleration values ascertained by sensors, in order to obtain preliminary individual values for the vehicle speed. The individual values for the vehicle velocity are weighted, the desired vehicle reference velocity being calculated as the mean value of the weighted individual velocities.
Ascertaining weighted variables for the individual wheel velocity values on the basis of a sensor system of an electronic stability program (ESP), which includes a lateral acceleration sensor, a yaw rate sensor, and four wheel speed probes, and calculating a mean value, which represents a support variable, as a function of the weighted wheel velocity values, is described in German Patent No. DE 199 36 710 A1.
Both in German Patent No. DE 102 59 272 A1 and also in German Patent No. DE 199 36 710 A1, the velocity variable to be ascertained is calculated on the basis of the free rolling wheel velocities, which are obtained from mathematical models, which only have a restricted validity, however. In the case of more complex models, via which the vehicle velocity may be ascertained with higher quality, a nonlinear model or a nonlinear algorithm is typically used, which may only be analyzed with increased computing effort, however.